Many semiconductors devices such as memory devices use delay lock circuits to generate an internal signal based on an external signal.
Some delay lock circuits use a feedback signal to obtain a measurement during an initialization. The feedback signal is a delayed version of the external signal. The measurement allows the delay lock circuits to synchronize the internal signal with the external signal.
Variations in elements such as manufacturing process, voltage, and temperature (PVT) may affect the measurement during the initialization. For example, the PVT variations may cause the delay lock circuits to spend more time to obtain the measurement, thereby increasing the time for the delay lock circuits to put the internal and external in synchronization. In some cases, the PVT variations may cause the delay lock circuits to fail to get the measurement during the initialization, leading to malfunction of the device.